Relatively sophisticated equipment has been suggested for displaying telephone numbers as they are called, and devices are also available for displaying the elapsed time of telephone calls. A problem remains unsolved, however, for achieving number display, timing display, and performing other telephone-related functions in a simple device easily attachable to existing telephones.
The invention involves recognition of this problem and realization of a way of producing a display of numbers being dialed and elapsed time for telephone calls in a device that attaches to the outside of a dial telephone without requiring any modification of an existing telephone. The inventive display accessory operates without any interconnection with telephone wiring or any necessity for entering the telephone housing and thus does not interfere with existing telephone functions. The invention also aims at simplicity, economy, and reliability in a compact and easy to install device for displaying telephone numbers dialed and elapsed time of telephone calls, and for performing other functions related to telephone use.